Stable aqueous colloidal silica product, and methods to make and use same

ABSTRACT

An aqueous colloidal silica product, a method of using the aqueous colloidal silica product, and a method of producing an aqueous colloidal silica product, are disclosed. The method of producing the aqueous colloidal silica product incorporates semi-batch addition of alkali metal silicate, which is capable of achieving an aqueous colloidal silica product having desirable physical and chemical characteristics. The aqueous colloidal silica product has been found to be particularly useful as an additive in a papermaking process.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 13/791,627, filed Mar. 8, 2013, the disclosure ofwhich is herein incorporated by reference in its entirety.

FIELD

At least one embodiment of the invention is directed to colloidal silicasols having high solids contents and low viscosity, while maintaininghigh surface area and enhanced stability. It is also directed to a newprocess involving a semi-batch addition for making such colloidal silicasols and to the use of such colloidal silica sols in a production ofpaper. At least one embodiment of the invention is directed to anaqueous colloidal silica product, a method of using an aqueous colloidalsilica product, and a method of producing an aqueous colloidal silicaproduct. The aqueous colloidal silica product is stable and has a lowerviscosity than thought to be achievable for products having a colloidalsilica solids concentration ranging from 16-18% by weight (i.e., 16-18%by weight of SiO₂ solids) and produced via conventional productionmethods.

BACKGROUND

This present invention is directed to colloidal silica sols having highsolids contents and low viscosity, while maintaining high surface areaand enhanced stability. It is also directed to a new process involving asemi-batch addition for making such colloidal silica sols and to the useof such colloidal silica sols in a production of paper. The colloidalsilica sols of the present invention uniquely exhibit high solidscontents in the range between about 16 to about 18% by weight of SiO₂solids, with viscosity ranging from about 4 to about 20 cPs, while thesaid colloidal silica sols still maintain high surface area and enhancedstability without modification of the surface with, for example,aluminum. Moreover the colloidal sols of the invention is prepared via anew semi-batch process, which is different from conventional silica solsprocess such as described in U.S. Pat. Nos. 6,372,806 and 6,372,089.Furthermore, the colloidal silica sols of the present inventionadvantageously exhibit excellent activity in many papermaking furnishes.The silica sols of present invention are useful, among other areas, inthe papermaking industry, for example, as retention and dewatering aids.

In contrast, the present invention provides a stable composition ofcolloidal silica sols that have concentration ranging from about 16 toabout 18 percent by weight of SiO₂ solids with low viscosity rangingfrom about 4 to about 20 cps, which is not in the teachings of the abovereference patents. The present invention provides stable silicacolloidal sols with high surface area and enhanced stability withoutmodify the surface with aluminum, as described in U.S. Pat. No.5,368,833.

BRIEF SUMMARY

In a first exemplary embodiment, the disclosure is directed to a stableaqueous colloidal silica product. The colloidal silica sols can beproduced and stored at concentrations of about 16 to about 18 percent byweight of SiO₂ solids, and remain stable at room temperature for atleast 30 days, typically for at least 180 days. The aqueous colloidalsilica product has a viscosity ranging from about 4 to about 20 cps andan S-value ranging from 26 to 40%. The colloidal silica solids have aspecific surface area ranging from 700 to 850 m²/g.

In a second exemplary embodiment, the disclosure is directed to a methodof producing an aqueous colloidal silica product. The method comprises,first, charging a reaction vessel with a cationic ion exchange resinhaving at least 40 percent, preferably at least 50 percent of its ionexchange capacity in the hydrogen form wherein the reaction vessel has,for example a screen near the bottom of the reaction vessel, forseparating the colloidal silica formed during the process from ionexchange resin. Second, charging the reaction vessel with water andstirring the contents of the reaction vessel. Third, adjusting thetemperature of the contents of the said reaction vessel to be in therange from 70 to 200 degrees Fahrenheit, preferably in the range from100 to 160 degrees Fahrenheit. Fourth, adding a first quantity of alkalimetal silicate to the said water and cationic ion exchange resin underagitation, thereby forming a first intermediate composition comprising afirst portion of aqueous colloidal silica product. Fifth, after 0 to 90minutes, a second quantity of alkali metal silicate is added to thefirst intermediate composition under agitation, thereby forming a secondintermediate composition comprising a second portion of aqueouscolloidal silica product. After about 0 minutes to 24 hours, the firstand second portions of aqueous colloidal silica products are separatedfrom the second intermediate composition, thereby producing the aqueouscolloidal silica product. The first and second quantity of alkali metalsilicate comprise a total quantity, with the first quantity ranging from60 to 95 weight percent of the total quantity. The first intermediatecomposition has a temperature ranging from 70 to 200 degrees Fahrenheitand a pH ranging from 8 to 14. The first quantity of alkali metalsilicate is added at a first rate sufficient to allow the first additionto last for 1 to 45 minutes. The second intermediate composition has atemperature ranging from 70 to 200 degrees Fahrenheit and a pH rangingfrom 9 to 11. The second quantity of alkali metal silicate is added at asecond rate sufficient to allow the second addition to last for 5 to 120minutes.

In a third exemplary embodiment, the disclosure is directed to a methodof making a cellulosic sheet. The method comprises preparing acellulosic furnish containing from 0.01 to 1.5 weight percent cellulosicfiber. An amount of aqueous colloidal silica product as described in thefirst exemplary embodiment is added to the cellulosic furnish. Theamount of aqueous colloidal silica product is sufficient to achieve aconcentration of colloidal silica solids of from about 0.00005 to about1.5 weight percent per dry weight of fiber in the cellulosic furnish. Anamount of a water soluble polymeric flocculant is added to thecellulosic furnish. The amount of water soluble polymeric flocculant issufficient to achieve a concentration of water soluble polymericflocculant of from about 0.001 to about 5 weight percent per dry weightof fiber in the cellulosic furnish. The water soluble polymericflocculant has a molecular weight ranging from 500,000 to 30 milliondaltons. The cellulosic furnish is then dewatered to obtain a cellulosicsheet.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the present disclosure will become more readilyapparent to those of ordinary skill in the relevant art after reviewingthe following detailed description and accompanying drawing, wherein:

FIG. 1 is a graph illustrating the improved first pass ash retention ofthree batches that incorporate the inventive aqueous colloidal silicaproduct of the present disclosure, as compared to a control sample.

DETAILED DESCRIPTION

While embodiments encompassing the general inventive concepts may takevarious forms, there will hereinafter be described various embodimentswith the understanding that the present disclosure is to be consideredmerely an exemplification, and the general inventive concepts are notintended to be limited to the disclosed embodiments.

All percentages, parts and ratios as used herein, are by weight of thetotal product, unless specified otherwise. All such weights as theypertain to listed ingredients are based on the active level and,therefore, do not include solvents or by-products that may be includedin commercially available materials, unless specified otherwise.

All references to singular characteristics or limitations of the presentdisclosure shall include the corresponding plural characteristic orlimitation, and vice versa, unless otherwise specified or clearlyimplied to the contrary by the context in which the reference is made.

All combinations of method or process steps as used herein can beperformed in any order, unless otherwise specified or clearly implied tothe contrary by the context in which the referenced combination is made.

All ranges and parameters, including but not limited to percentages,parts, and ratios, disclosed herein are understood to encompass any andall sub-ranges assumed and subsumed therein, and every number betweenthe endpoints. For example, a stated range of “1 to 10”should beconsidered to include any and all subranges between (and inclusive of)the minimum value of 1 and the maximum value of 10; that is, allsubranges beginning with a minimum value of 1 or more (e.g., 1 to 6.1)and ending with a maximum value of 10 or less (e.g., 2.3 to 9.4, 3 to 8,4 to 7), and finally to each number 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10contained within the range.

Ordinal numbers (e.g., first, second, third, etc.) may be utilizedherein to describe various aspects of the present disclosure that may besimilar. For example, two adding steps may be defined using ordinalnumbers (e.g., “first adding” and “second adding”). When utilized, theordinal numbers are used for the purposes of differentiating one elementfrom another similarly-named element, thereby allowing for clarity inreferencing the similarly-named elements. The ordinal numbers should notbe construed as necessarily limiting the order of elements, unlessclearly defined by the context of the disclosure.

The various embodiments of the compositions and products of the presentdisclosure may also be substantially free of any optional ingredient orfeature described herein, provided that the remaining composition orproduct still contains all of the required ingredients or features asdescribed herein. In this context, and unless otherwise specified, theterm “substantially free” means that the selected composition or productcontains less than a functional amount of the optional ingredient,typically less than about 1%, including less than about 0.5%, includingless than about 0.1%, and also including zero percent, by weight of suchoptional ingredient.

The compositions and products may comprise, consist of, or consistessentially of the required elements of the products as describedherein, as well as any additional or optional element described hereinor otherwise useful in product applications.

The term “aqueous” as used herein, unless otherwise specified, isintended to be construed as a modifier that means “water-containing” or“in water,” as opposed to “oil-containing” or “in oil.” For purposes ofthis disclosure, “water” refers to liquid water. An aqueous compositionmay be liquid water, a solution having liquid water as a solvent, or aslurry of solids in liquid water. Notably, a silica sol is an aqueouscomposition, as it comprises colloidal silica solids in liquid water.

The term “colloid” as used herein, unless otherwise specified, isintended to be construed as a substance containing ultra-small particlessubstantially evenly dispersed throughout another substance. The colloidconsists of two separate phases: a dispersed phase (or internal phase)and a continuous phase (or dispersion medium) within which the dispersedphase particles are dispersed. The dispersed phase particles may besolid, liquid, or gas. The dispersed-phase particles may have a diameterranging from about 1 to 1,000,000 nanometers. The colloid may besubstantially affected by the surface chemistry present in thedispersed-phase particles. An exemplary embodiment of a colloid is anaqueous colloidal silica product. Exemplary embodiments ofdispersed-phase particles are colloidal silica solids.

The term “colloidal silica” as used herein, unless otherwise specified,is intended to be construed as a colloid in which the primarydispersed-phase particles comprise silicon containing molecules. Thisdefinition includes the full teachings of the reference book: TheChemistry of Silica: Solubility, Polymerization, Colloid and SurfaceProperties and Biochemistry of Silica, by Ralph K. Iler, John Wiley andSons, Inc. (1979), in general, and particularly pages 312-599. When theparticles have a diameter of above 100 nm, the particles may be referredto as “sols,” “silica sols,” “aquasols,” or “nanoparticles.”

The term “product” as used herein, unless otherwise specified, isintended to be construed as a substance that is created from a chemicalreaction or a series thereof and capable of being utilized as aningredient in a manufacturing process. As used herein, a “product” isgenerally a portion of the composition that results from the chemicalreaction or series thereof.

The term “aqueous colloidal silica product” (or “AqCSP”) as used herein,unless otherwise specified, is intended to be construed as a homogenousmixture with dispersed silica particles/aggregates in aqueous phase thatwere created from a chemical reaction or a series thereof, and capableof being utilized as an ingredient in a manufacturing process,particularly in a papermaking process. In certain embodiments, an“aqueous colloidal silica product” is a silica sol.

The term “silica sol” as used herein, unless otherwise specified, isintended to be construed as a homogenous aqueous mixture compositioncontaining colloidal silica particles or aggregates.

In the event that the above definitions or a description statedelsewhere in this application is inconsistent with a meaning (explicitor implicit) which is commonly used, in a dictionary, or stated in asource incorporated by reference into this application, the applicationand the claim terms in particular are understood to be construedaccording to the definition or description in this application, and notaccording to the common definition, dictionary definition, or thedefinition that was incorporated by reference. In light of the above, inthe event that a term can only be understood if it is construed by adictionary, if the term is defined by the Kirk-Othmer Encyclopedia ofChemical Technology, 5th Edition, (2005), (Published by Wiley, John &Sons, Inc.) this definition shall control how the term is to be definedin the claims.

In at least one embodiment colloidal silica sols uniquely exhibit highsolids contents in the range between about 16 to about 18% by weight ofSiO₂ solids, with viscosity ranging from about 4 to about 20 cPs, whilethe said colloidal silica sols still maintain high surface area andenhanced stability without modification of the surface with, forexample, aluminum. Moreover the colloidal sols of the invention isprepared via a new semi-batch process, which is different conventionalsilica sols process such as described in U.S. Pat. Nos. 5,368,833,6,372,806 and 6,372,089. Furthermore, the colloidal silica sols of thepresent invention advantageously exhibit excellent activity in manypapermaking furnishes. The silica sols of present invention are useful,among other areas, in the papermaking industry, for example, asretention and dewatering aids.

At least one embodiment is a stable composition of colloidal silica solsthat have concentration ranging from about 16 to about 18 percent byweight of SiO₂ solids with low viscosity ranging from about 4 to about20 cps, which is not accomplished according to the teachings of theabove reference patents. In particular the sol may exclude the presenceof aluminum yet has as high or higher surface area and/or is as stable,or more stable than those sols described in U.S. Pat. No. 5,368,833.

At least one embodiment is directed to an aqueous colloidal silicaproduct. The aqueous colloidal silica product comprises water and from16 to 18 weight percent colloidal silica solids. The aqueous colloidalsilica product has a viscosity ranging from about 4 to about 20 cps andan S-value ranging from 26 to 40%. The colloidal silica solids have aspecific surface area ranging from 700 to 850 m²/g.

At least one embodiment is directed to a method of producing an aqueouscolloidal silica product. The method comprises, first, charging areaction vessel with a cationic ion exchange resin having at least 40percent, preferably at least 50 percent of its ion exchange capacity inthe hydrogen form wherein the reaction vessel has for example a screennear the bottom of the reaction vessel, for separating the colloidalsilica formed during the process from ion exchange resin. Second,charging the reaction vessel with water and stirring the contents of thereaction vessel. Third, adjusting the temperature of the contents of thesaid reaction vessel to be in the range from 70 to 200 degreesFahrenheit, preferably in the range from 100 to 160 degrees Fahrenheit.Fourth, adding a first quantity of alkali metal silicate to the saidwater and cationic ion exchange resin under agitation, thereby forming afirst intermediate composition comprising a first portion of aqueouscolloidal silica product. Fifth, after 0 to 90 minutes, a secondquantity of alkali metal silicate is added to the first intermediatecomposition under agitation, thereby forming a second intermediatecomposition comprising a second portion of aqueous colloidal silicaproduct. After about 0 minutes to 24 hours, the first and secondportions of aqueous colloidal silica products are separated from thesecond intermediate composition, thereby producing the aqueous colloidalsilica product. The first and second quantity of alkali metal silicatecomprise a total quantity, with the first quantity ranging from 60 to 95weight percent of the total quantity. The first intermediate compositionhas a temperature ranging from 70 to 200 degrees Fahrenheit and a pHranging from 8 to 14. The first quantity of alkali metal silicate isadded at a first rate sufficient to allow the first addition to last for1 to 45 minutes. The second intermediate composition has a temperatureranging from 70 to 200 degrees Fahrenheit and a pH ranging from 9 to 11.The second quantity of alkali metal silicate is added at a second ratesufficient to allow the second addition to last for 5 to 120 minutes.

At least one embodiment is directed to a method of making a cellulosicsheet. The method comprises preparing a cellulosic furnish containingfrom 0.01 to 1.5 weight percent cellulosic fiber. An amount of aqueouscolloidal silica product as described in the first exemplary embodimentis added to the cellulosic furnish. The amount of aqueous colloidalsilica product is sufficient to achieve a concentration of colloidalsilica solids of from about 0.00005 to about 1.5 weight percent per dryweight of fiber in the cellulosic furnish. An amount of a water solublepolymeric flocculant is added to the cellulosic furnish. The amount ofwater soluble polymeric flocculant is sufficient to achieve aconcentration of water soluble polymeric flocculant of from about 0.001to about 5 weight percent per dry weight of fiber in the cellulosicfurnish. The water soluble polymeric flocculant has a molecular weightranging from 500,000 to 30 million daltons. The cellulosic furnish isthen dewatered to obtain a cellulosic sheet.

At least one embodiment is directed to an aqueous colloidal silicaproduct having certain chemical and physical characteristics. While aperson of skill in the art will readily recognize that the methods ofthe second exemplary embodiment may be used to produce the firstexemplary embodiment, the first exemplary embodiment should not beconstrued as limited to the method of the second exemplary embodiment.In other words, the aqueous colloidal silica product may be produced bymethods that differ from those of the second embodiment.

In at least one embodiment the aqueous colloidal silica product comprisecolloidal silica solids at a concentration ranging from 16 to 18 weightpercent, or 16 to 17, or 17 to 18, of the aqueous colloidal silicaproduct. In certain exemplary embodiments, the aqueous colloidal silicaproduct comprises colloidal silica solids at a concentration of at least16 weight percent, or at least 16.2 weight percent, or at least 16.5weight percent, or at least 16.6 weight percent, or at least 16.7 weightpercent, or at least 16.8 weight percent, or at least 16.9 weightpercent, or at least 17 weight percent, up to 18 weight percent.

Viscosity of the aqueous colloidal silica product is a parameter thatcan be important to the manufacturers and users of aqueous colloidalsilica products. The aqueous colloidal silica products need to flowthrough the cationic resin bed and pipes with relative ease in order tobe useful in manufacturing processes. According to the first exemplaryembodiment of the present disclosure, the aqueous colloidal silicaproduct has a viscosity ranging from about 4 to about 20 cps. In certainembodiments, the aqueous colloidal silica product has a viscosity of atleast about 4 cps, and up to 20 cps, or up to 18 cps, or up to 15 cps,or up to 12 cps, or up to 10 cps, or up to 8 cps. In certainembodiments, the aqueous colloidal silica product has a viscosityranging from 4 to 18 cps, or 4 to 15 cps, or 4 to 10 cps.

The S-value of the aqueous colloidal silica product is another parameterthat may be monitored and reported to users of aqueous colloidal silicaproducts. S-value is a quantification of the degree of microaggregationof colloidal materials. The exact definition of S-value can be found inThe Chemistry of Silica: Solubility, Polymerization, Colloid and SurfaceProperties and Biochemistry of Silica, by Ralph K. Iler, John Wiley andSons, Inc. (1979). According to the first exemplary embodiment of thepresent disclosure, the aqueous colloidal silica product has an S-valueranging from 26 to 40%. In certain embodiments, the aqueous colloidalsilica product has an S-value of at least 26%, or at least 27%, or atleast 28%, or at least 29%, and up to 40%, or up to 39%, or up to 38%,or up to 37%, or up to 36%, or up to 35%, or up to 34%, or up to 33%, orup to 32%, or up to 31%, or up to 30%. In certain embodiments, theaqueous colloidal silica product has an S-value ranging from 28 to 40%,or 29 to 39%.

Specific surface area of the colloidal silica solids in an aqueouscolloidal silica product is a parameter that may be monitored andreported to users of the aqueous colloidal silica product. Specificsurface area is reported in units of area per weight or mass of asubstance (e.g., m²/g). The first exemplary embodiment of the presentdisclosure comprises colloidal silica solids having a specific surfacearea ranging from 700 to 850 m²/g. In certain embodiments, the aqueouscolloidal silica product comprises colloidal silica solids having aspecific surface area of at least 700 m²/g, or at least 750 m²/g, or atleast 800 m²/g, and up to 850 m²/g. In certain embodiments, thecolloidal silica solids of the aqueous colloidal silica product have aspecific surface area ranging from 750 to 850 m²/g, or 800 to 850 m²/g.

The aqueous colloidal silica products may be considered to be stable forat least 30 days. In certain embodiments, the aqueous colloidal silicaproduct is stable for at least 60 days, or at least 90 days, or at least120 days, or at least 180 days, and, in certain embodiments, up to 360days or more. In certain embodiments, the aqueous colloidal silicaproduct is stable for 30 to 360 days, or from 60 to 360 days, or from 90to 360 days, or 120 to 360 days, or 180 to 360 days. By “stable,” it ismeant that the aqueous colloidal silica product retains its physical andchemical properties related to one or more of weight percent colloidalsilica solids, viscosity, S-value, and specific surface area at least atthe broadest levels defined herein, even in the event that the aqueouscolloidal silica product is no longer agitated. In other words, theaqueous colloidal silica product does not substantially degrade or loseits ability to be used in a manufacturing process, such as a papermakingprocess.

Aluminum or aluminum-containing compounds are sometimes added to aqueouscolloidal silica products to treat the surface area of the colloidalsilica solids, thereby stabilizing the aqueous colloidal silica product.The embodiments of the aqueous colloidal silica product disclosed hereinare generally aluminum-free and do not need to be treated with aluminumor aluminum-containing compounds in order to maintain their stability.In certain embodiments, the aqueous colloidal silica product isaluminum-free and stable for at least 30 days, or at least 60 days, orat least 90 days, or at least 120 days, or at least 180 days, and up to360 days. In certain embodiments, the aqueous colloidal silica productis stable for 30 to 360 days, or from 60 to 360 days, or from 90 to 360days, or 120 to 360 days, or 180 to 360 days. The term “aluminum-free”indicates that the aqueous colloidal silica product contains no morethan trace amounts of aluminum or aluminum-containing compounds, e.g.,less than 500 ppm aluminum.

In certain embodiments of the aqueous colloidal silica product, theaqueous colloidal silica product further comprises an alkali metal oralkali metal-containing compound. The alkali metal or alkalimetal-containing compound may be in the form of an alkali metal ion, analkali metal oxide, an alkali metal silicate, an alkali metal salt, oranother form known to those of skill in the art. A suitable alkalimetal-containing compound used to make certain embodiments of theaqueous colloidal silica product is an alkali metal silicate, asdescribed herein. Exemplary embodiments of alkali metals that may bepresent in the aqueous colloidal silica product include sodium,potassium, lithium and combinations thereof. Certain embodiments of theaqueous colloidal silica product further comprise a sodium-containingcompound.

In embodiments of the aqueous colloidal silica product that furthercomprise an alkali metal or alkali metal-containing compound, the alkalimetal or alkali metal-containing compound may be present in the aqueouscolloidal silica product in an amount sufficient to provide a molarratio of silica to alkali metal ranging from 5:1 to 50:1, or 5:1 to30:1, or 5:1 to 25:1, or 5:1 to 20:1, or 5:1 to 15:1. In certainembodiments, the aqueous colloidal silica product has a molar ratio ofSiO₂ to alkali metal of at least 8:1 and up to 50:1, or up to 30:1, orup to 25:1, or up to 20:1, or up to 15:1.

Certain embodiments of the aqueous colloidal silica product have a pHranging from 9 to 11. The pH of the aqueous colloidal silica product mayfurther range from 10 to 11.

At least one embodiment is directed to a method of producing an aqueouscolloidal silica product. In an embodiment any of the above method(s)may be utilized to produce the aqueous colloidal silica product of thefirst exemplary embodiment of the present disclosure. However, the abovemethods are not limited so as to only produce only the above aqueouscolloidal silica product. Furthermore, because the addition of thealkali metal silicate is performed in two steps, the method of producingan aqueous colloidal silica product may be described as “semi-batch” asopposed to “batch.”

In at least one embodiment a first quantity of alkali metal silicate isadded to water and a partially regenerated cationic ion exchange resinunder agitation and at a temperature ranging from 70 to 200 degreesFahrenheit, thereby forming a first intermediate composition comprisinga first portion of aqueous colloidal silica product. The firstintermediate composition has a pH of 8 to 14, or 8 to 12, or 9 to 11,and in certain embodiments, a pH of at least 8, or at least 9 or atleast 10, and up to 14, or up to 13, or up to 12, or up to 11. The firstquantity of alkali metal silicate is added to the water and cationic ionexchange resin at a rate sufficient to allow the addition to last for 1to 45 minutes, or 2 to 30 minutes, and in certain embodiments, for atleast 1, or at least 2 minutes, and up to 45, or up to 30, or up to 20,or up to 10 minutes.

After the first quantity of the alkali metal silicate is added, a secondquantity of alkali metal silicate is added to the first intermediatecomposition under agitation and at a temperature ranging from 70 to 200degrees Fahrenheit, thereby forming a second intermediate compositioncomprising a second portion of aqueous colloidal silica product. Thesecond quantity may be added at any time from just after the addition ofthe first quantity of alkali metal silicate is completed (e.g., 0minutes), up to 90 minutes after the addition of the first quantity. Thesecond intermediate composition has a pH ranging from 8 to 11, or from 9to 11. The second quantity of alkali metal silicate is added at a secondrate sufficient to allow the addition to last for 5 to 120 minutes, or10 to 60 minutes, and in certain embodiments, for at least 5 minutes, orat least 10 minutes, or at least 15 minutes, up to 120 minutes, or up to90 minutes, or up to 60 minutes, or up to 45 minutes, or up to 30minutes.

In certain embodiments of the method of producing an aqueous colloidalsilica product, the second intermediate composition is allowed toagitate for 0 minutes to 24 hours, and in certain embodiments for atleast 0 minutes, or at least 15 minutes, or at least 30 minutes, up to24 hours, or up to 18 hours, or up to 12 hours, or up to 6 hours, or upto 3 hours, or up to 2 hours. In certain embodiments of the method ofproducing the aqueous colloidal silica product, the first or secondintermediate products, or both, may be agitated in any one or multiplemanners known to the person of skill in the art, including, but notlimited to, impeller or paddle mixing, recirculation, air sparging,vibration, vessel shaking, and combinations thereof.

After 0 minutes to 24 hours of agitation, the first and second portionsof aqueous colloidal silica product are separated from the secondintermediate composition, thereby producing the aqueous colloidal silicaproduct. In certain embodiments, the separation of the aqueous colloidalsilica product from the second intermediate composition is performedusing filtration.

In at least one embodiment, the filtration is performed using anothertype of liquid/solid separating device constructed and arranged toremove suspended material from a liquid carrier medium. This may beaccomplished by any filtration device such as a screen,slotted/perforated pipe, membrane or similar crude filtration device, orcombinations thereof. Representative examples include but are notlimited to sand filters, filter paper, membrane filters, RO, NF, UF, MF,submerged filters, pressure filters, (centrifuges, cyclones,hydrocyclones, electrostatic precipitators, gravity separators, misteliminators, screeners, steam traps, absorbers, adsorbers, biofilters,crystalizers, dehumidifiers, distillation columns, dryers, evaporators,extractors, humidifiers, ion exchange columns, strippers), and anycombination thereof. In at least one embodiment the filter includes oneor more of the filtration techniques disclosed in paper Terminology forMembranes and Membrane Processes, by W J Koros et al., Journal ofMembrane Science, Vol. 120 pp. 149-159 (1996). In at least oneembodiment the filter comprises any one or more of the chemicalseparation processes described on the website:http://encyclopedia.che.engin.umich.edu/Pages/SeparationsChemical/SeparationsChemical.html(as accessed on Oct. 17, 2013) and/or any one or more of the mechanicalprocesses described on the website:http://encyclopedia.che.engin.umich.edu/Page/SeparationsMechanical/SeparationsMechanical.html(as accessed on Oct. 17, 2013). Membrane filter may be made ofpolymeric, ceramic, steel or glass materials.

According to an embodiment, in the method of producing, e.g., aqueouscolloidal silica product, the first quantity and the second quantity ofalkali metal silicate comprise a total quantity, with the first quantityranging from 60 to 95 weight percent, or 65 to 90 weight percent, or 70to 80 weight percent, of the total quantity, and in certain embodimentsbeing at least 60 weight percent, or at least 65 weight percent, or atleast 70 weight percent, up to 95 weight percent, or up to 90 weightpercent, or up to 85 weight percent or up to 80 weight percent, or up to75 weight percent of the total quantity.

Generally, the alkali metal silicate (both the first and secondquantities thereof) that is added in the method of the second exemplaryembodiment is selected from the group consisting of sodium silicate,potassium silicate, lithium silicate and combinations thereof. Incertain embodiments, the alkali metal silicate is sodium silicate. Whilethe first and second quantities of alkali metal silicate are generallythe same composition (e.g., generally having the same chemicalcomposition, same physical properties, same impurities, etc.), the firstand second quantities can in theory be compositions having differingphysical or chemical characteristics. For example, the first quantity issodium silicate and the second quantity is potassium silicate. Incertain embodiments, the first and second quantities of the alkali metalsilicate are the same composition. For example, the first quantity issodium silicate and the second quantity is the same type of sodiumsilicate.

While the quality of the starting ingredients (i.e., alkali metalsilicate, cationic ion exchange resin, water, etc.) may provide somevariation in the aqueous colloidal silica product, the method hasunexpectedly produced aqueous colloidal silica product having propertiesparticularly beneficial to the papermaking industry, for example asretention and dewatering aids. The alkali metal silicate can be anynumber of conventional materials, such as water glasses. The mole ratioof SiO₂ to Na₂O, or K₂O, or Li₂O, or combination of Na₂O, K₂O and Li₂O,in the alkali metal silicate, can be in the range from 15:1 to 1:1 andis preferably within the range from 2.5:1 to 3.9:1. Such alkali metalsilicate solution typically will have a pH in excess of 10, typically atleast 11. Such alkali metal may contain impurities, include but notlimited to aluminum, iron, calcium, magnesium, chloride, and sulfateions. The solids contains in the said alkali metal silicate can in therange from about 15 to 40 percent by weight as SiO₂.

The water used in producing the aqueous colloidal silica product is notparticularly limited and may be any reasonably soft fresh water (i.e.,not brine and having less than 2000 S/cm conductance). In certainembodiments, the water is tap water, well water, distilled water,deionized water, otherwise purified water, or any combination thereof.

The cationic ion exchange resin utilized in the methods of the secondexemplary embodiment is not particularly limited. In certainembodiments, the cationic ion exchange resin is preferable to be a weakacid cationic resin, includes but not limited to, Amberlite® IRC84SP.

In certain embodiments, the cationic ion exchange resin may be reusedfrom previous production processes after regeneration. The cationic ionexchange resin may be regenerated using an organic or mineral acid.Exemplary embodiments of acids that may be used to regenerate thecationic ion exchange resin include, but are not limited to, thefollowing: sulfuric acid, hydrochloric acid, phosphoric acid, or suchmaterials as carbon dioxide, and combinations thereof. Examples ofsuitable organic acids include but are not limited to: acetic acid,formic acid and propionic acid. In certain embodiments, mineral andorganic salts may be used as a weak acid to regenerate the resin or beused to reduce the colloidal silica product viscosity. Example ofsuitable salts includes but not limited to: sodium sulfate, sodiumacetate, potassium sulfate, potassium acetate, trisodium phosphate andsodium monohydrogen phosphate.

While the cationic ion exchange resin has an ion exchange capacity inthe hydrogen form that is not particularly limited, in certainembodiments, the cationic ion exchange resin has an ion exchangecapacity of 40 to 100%, or 50 to 100% or 60 to 100%, and in certainembodiments at least 40%/c, or at least 50%, or at least 60%, in thehydrogen form.

Unexpectedly, methods according to the second embodiment have been shownto be capable of producing an aqueous colloidal silica product havingfrom 16 to 18 weight percent colloidal silica solids, a viscosityranging from 4 to 20 cps, an S-value ranging from 26 to 40%, and withcolloidal silica solids having a specific surface area ranging from 700to 850 m²/g, all without using silicic acid or ultrafiltration.

In certain embodiments of the second exemplary embodiment, the first orsecond intermediate composition, the aqueous colloidal silica product,or any, or all of the aforementioned have a pH ranging from 8 to 11, andthe pH may further range from 9 to 11.

In certain embodiments of the second exemplary embodiment, the first andsecond intermediate compositions have temperatures ranging from 100 to160 degrees Fahrenheit.

In certain embodiments of the second exemplary embodiment, the firstrate of adding the alkali metal silicate is sufficient to allow theaddition of the first quantity of alkali metal silicate to last from 1to 45 minutes. In certain embodiments of the second exemplaryembodiment, the second rate of adding the alkali metal silicate issufficient to allow the addition of the second quantity of alkali metalsilicate to last from 5 to 120 minutes.

The aqueous colloidal silica product described herein may be used in anyone or more of several manufacturing processes, including, but notlimited to, the following: papermaking processes, for example, retentionand drainage, pulp dewatering; water treatment and wastewater treatmentprocesses, for example sludge dewatering, clarification and dewateringof aqueous mineral slurries, refinery emulsion breaking and the like;food and beverage processes, for example, for beer, wine, juice, andsugar clarification. The aqueous colloidal silica product describedherein is particularly suited for use in the papermaking process.

The method may be used according to any one, some, or all, of themethods and processes for utilizing colloidal silica as described in theHandbook for Pulp and Paper Technologists, by Gary A. Smook, Angus WildePublicatiosn Inc., (2001). In addition, the aqueous colloidal silicaproduct can be added to a cellulosic furnish at the wet end of thepapermaking process, thereby enhancing the retention of filler (“ash”)in the cellulosic furnish, and consequently in the cellulosic sheet,while further aiding in the drainage of water from the cellulosicfurnish.

At least one embodiment of the present disclosure is directed to amethod of making a cellulosic sheet. The method comprises preparing acellulosic furnish containing from 0.01 to 1.5 weight percent cellulosicfiber based upon the total weight of the cellulosic furnish (i.e.,including water). An amount of an aqueous colloidal silica product asdescribed herein, and an amount of a water soluble polymeric flocculant,is added to the cellulosic furnish. The amount of the aqueous colloidalsilica product added to the cellulosic furnish is sufficient to achievea concentration of colloidal silica solids of from about 0.00005 toabout 1.5 weight percent per dry weight of fiber in the cellulosicfurnish. In other words, for every 100 lbs of fiber (dry weight) in thecellulosic furnish, 0.00005 to 1.5 lbs of colloidal silica solids willbe present. The amount of the water soluble polymeric flocculant addedto the cellulosic furnish is sufficient to achieve a concentration ofwater soluble polymeric flocculant of from about 0.001 to about 5 weightpercent per dry weight of fiber in the cellulosic furnish. The watersoluble polymeric flocculant has a molecular weight ranging from 500,000to 30 million daltons. The cellulosic furnish is then dewatered in afashion known by those of skill in the art to thereby obtain acellulosic sheet. A cationic starch may alternatively be added to thefurnish in place of, or in addition to the synthetic polymer flocculantin an amount of from about 0.005 to about 5.0 percent by weight based onthe dry weight of fiber in furnish. More preferably, the starch is addedin an amount of from about 0.5 to about 1.5 percent by weight based onthe dry weight of fiber in the furnish. In yet another embodiment, acoagulant may be added to the furnish in place of, or in addition to,the flocculant and/or the starch in an amount of from about 0.005 toabout 1.25 percent by weight based on the dry weight of fiber in thepapermaking furnish. Preferably, the coagulant is added in an amount offrom about 0.025 to about 0.5 percent by weight based on the dry weightof fiber in the furnish.

In certain embodiments of the method of making the cellulosic sheet, theaqueous colloidal silica product is added to the cellulosic furnish.

Non-limiting examples of water soluble polymeric flocculants suitablefor use in certain embodiments according to the third exemplaryembodiment include cationic, anionic, amphoteric, and zwitterionicpolymers. Examples of cationic water soluble polymer flocculants includecationized starch, and homopolymers and copolymers comprising thefollowing monomers: dimethylaminoethyl methacrylate (“DMAEM”),dimethylaminoethyl acrylate (“DMAEA”), diethylaminoethyl acrylate(“DEAEA”), diethylaminoethyl methacrylate (“DEAEM”), or their quaternaryammonium forms made with dimethyl sulfate or methyl chloride; mannichreaction modified polyacrylamides; diallylcyclohexylamine hydrochloride(“DACHA HCl”); diallyldimethylammonium chloride (“DADMAC”);methacrylamidopropyltrimethylammonium chloride (“MAPTAC”); and allylamine (“ALA”).

In certain embodiments, the amount of the aqueous colloidal silicaproduct added to the cellulosic furnish is sufficient to achieve acolloidal silica solids concentration of 0.00005 to 1.5 weight percent,or 0.0005 to 1 weight percent, or 0.005 to 0.05 weight percent, per dryweight of fiber in the cellulosic furnish, and in certain embodimentsfrom at least 0.00005, or at least 0.0005, or at least 0.005, or atleast 0.05, up to 0.5, or up to 1, or up to 1.5 weight percent per dryweight of fiber in the cellulosic furnish.

First pass ash retention (“first pass ash retention” or “FPAR”) is aparameter that is important to papermakers when determining fillerretention in the cellulosic furnish, and consequently in the cellulosicsheet. Aqueous colloidal silica product added to the cellulosic furnishallows for increased first pass ash retention, while not detrimentallyaffecting the water drainage from the cellulosic furnish. In fact, theaqueous colloidal silica product of the present disclosure has beenfound to aid in water drainage from the cellulosic furnish.

Furthermore, the first pass ash retention can be used to calculate afirst pass ash retention replacement ratio, which is a ratio of theamount of microparticle dose needed to achieve an equivalent first passash retention when utilizing the aqueous colloidal silica product of thepresent disclosure as compared to when utilizing an aqueous colloidalsilica product produced using the batch process known in the art (suchas U.S. Pat. Nos. 6,372,089 and 6,372,806). The first pass ash retentionreplacement ratio is illustrated in Equation 1 below:

$\begin{matrix}{{{FPAR}\mspace{14mu} {Replacement}\mspace{14mu} {Ratio}} = \frac{\begin{matrix}{{Microparticle}\mspace{14mu} {Dose}\mspace{14mu} {for}\mspace{14mu} {Cellulosic}\mspace{14mu} {Sheet}} \\{{Utilizing}\mspace{14mu} {AqCSP}\mspace{14mu} {to}\mspace{14mu} {acheive} \times {FPAR}}\end{matrix}}{\begin{matrix}{{Microparticle}\mspace{14mu} {Dose}\mspace{14mu} {for}\mspace{14mu} {Cellulosic}\mspace{14mu} {Sheet}} \\{{Utilizing}\mspace{14mu} {Batch}\mspace{14mu} {AqCSP}\mspace{14mu} {to}\mspace{14mu} {achieve} \times {FPAR}}\end{matrix}}} & (1)\end{matrix}$

As can be deduced from Equation 1 and as illustrated in FIG. 1,improvement in the first pass ash retention is shown when the FPARreplacement ratio is less than one. For cellulosic sheets utilizing a“batch” aqueous colloidal silica product and achieving a first pass ashretention of 90%, the microparticle dose required to achieve the 90%FPAR is approximately 1.6 lb of microparticles per ton of cellulosicfurnish, based on dry cellulosic fibers. In certain embodiments,cellulosic sheets incorporating the aqueous colloidal silica product ofthe present disclosure, and at the same colloidal silica solids amountper dry weight of fiber, has been shown to be capable of achieving a 90%FPAR at about 0.9 to about 1.2 lb of microparticles per ton dry weightof fiber in the cellulosic furnish. Thus, in certain embodiments, theFPAR replacement ratio for a cellulosic sheet incorporating theinventive aqueous colloidal silica product ranges from about 0.5 toabout 0.8.

EXAMPLES

The foregoing may be better understood by reference to the followingexamples, which are presented for purposes of illustration and are notintended to limit the scope of the invention. In particular the examplesdemonstrate representative examples of principles innate to theinvention and these principles are not strictly limited to the specificcondition recited in these examples. As a result it should be understoodthat the invention encompasses various changes and modifications to theexamples described herein and such changes and modifications can be madewithout departing from the spirit and scope of the invention and withoutdiminishing its intended advantages. It is therefore intended that suchchanges and modifications be covered by the appended claims.

Example 1

Preparation of a Colloidal Silica Sol of the Invention. Inventiveaqueous colloidal silica products (Samples 7-15 in Table 1) wereprepared using the lab-scale semi-batch procedure described as follows.Charge a reaction vessel with 600 mL of Amberlite® IRC84SP ion exchangeresin (available from Dow) in its sodium form. Following manufacturer'sprocedure for regenerating the resin to the hydrogen form such that theregeneration is at least 40 percent complete. Rinse the resin clean withwater and drain the water. Charge 190-380 grams of water into the vesseland start mixing the contents of the vessel to suspend the resin. Next,heat the contents of the reactor to 100-160 degrees F. Charge thereaction vessel (over a period of about 2-20 minutes) with 186-505 gramsof sodium silicate (having a mole ratio of SiO₂ to Na₂O of 3.26 and a pHof 11.2). After 1-45 min, charge the reaction vessel (over a period ofabout 5-30 minutes) with 13-160 grams of sodium silicate. Stir thecontents in the reaction vessel for another 10-180 minutes. Then, removethe contents from the reaction vessel and separate the colloidal silicaproduct from ion exchange resin via a filter bag.

Preparation of a Colloidal Silica Sol using conventional batch process.For comparative samples produced using the batch method (Sample 1-6).Charge a reaction vessel with 600 mL of Amberlite® IRC84SP ion exchangeresin (available from Dow) in its sodium form. Following manufacturer'sprocedure for regenerating the resin to the hydrogen form such that theregeneration is at least 40 percent complete. Rinse the resin clean withwater and drain the water. Charge 190-380 grams of water into the vesseland start mixing the contents of the vessel to suspend the resin. Next,heat the contents of the reactor to 100-160 degrees F. Charge thereaction vessel (over a period of about 2-20 minutes) with 266-532 gramsof sodium silicate (having a mole ratio of SiO₂ to Na₂O of 3.26 and a pHof 11.2). Stir the contents in the reaction vessel for another 10-180minutes. Then, remove the contents from the reaction vessel and separatethe colloidal silica product from ion exchange resin via a filter bag.

TABLE 1 Lab-scale Samples Prepared via Batch Method (Samples 1-6) orInventive Semi-batch Method (Samples 7-15) SiO₂ Addition, Batch (“B”) orColloidal Specific Semi- Silica Solids Surface S- batch concentrationViscosity Conductivity, Area value Sample (“S”) (wt %) pH (cP) μS/cm(m²/g) (%) 1 B 16.02 10.26 41.2 5560 831 25.8 2 B 16.37 10.46 22.2 6610850 27.2 3 B 16.05 11.13 50 10260 870 18.9 4 B 16.49 10.78 25 6870 86926.5 5 B 16.68 10.14 25 6710 888 27.9 6 B 17.07 n/a 58 n/a n/a 28.0 7 S16.80 10.48 5.46 7210 832 33.1 8 S 16.5 10.22 10.3 6400 836 33.1 9 S16.4 10.11 13.2 5330 719 32.6 10 S 16.4 10.39 9.2 6180 770 30.7 12 S17.2 10.24 15.6 6700 836 29.6 13 S 16.5 9.9 16.5 5820 777 32.6 14 S 16.79.9 13.8 5810 789 34.8 15 S 17.1 10.21 11.4 6500 846 33.0

As can be seen from Table 1, the samples prepared by the conventionalbatch method that achieve at least 16% colloidal silica solids (e.g.,Samples 1-6) all fail to meet the claimed upper limit related toviscosity. However, Samples 7-15, prepared using the semi-batch methodoutlined herein, all unexpectedly achieved 16-18 weight percentcolloidal silica solids while meeting the claim limitations recited forviscosity (4-20 cP), S-value (26-35%), and specific surface area of thecolloidal silica solids (700-850 m²/g).

Example 2

For Example 2, inventive aqueous colloidal silica products (Samples16-29 in Table 2) were prepared using the following pilot-scalesemi-batch procedure. Charge a reaction vessel with 185 gallons ofAmberlite® IRC84SP ion exchange resin (available from Dow) in its sodiumform. Following manufacturer's procedure for regenerating the resin tothe hydrogen form such that the regeneration is at least 40 percentcomplete. Rinse the resin clean with water and drain the water. Charge683-1158 lbs of water into the vessel and start mixing the contents ofthe vessel to suspend the resin. Next, heat the contents of the reactorto 100-160 degrees F. Charge the reaction vessel (over a period of about2-20 minutes) with 574-1320 lbs of sodium silicate (having a mole ratioof SiO₂ to Na₂O of 3.26 and a pH of 11.2). After 1-45 min, charge thereaction vessel (over a period of about 5-30 minutes) with 41-417 lbs ofsodium silicate. Stir the contents in the reaction vessel for another10-180 minutes. Then, remove the contents from the reaction vessel fromthe bottom through the screen.

TABLE 2 Pilot-scale Samples Prepared via Inventive Semi-batch MethodColloidal Silica Solids Specific concentration Viscosity Surface AreaS-value Sample (wt %) pH (cP) (m²/g) (%) 16 17.8 10.7 11 766 34.0 1717.3 10.6 14 773 30.9 18 17.3 10.6 15 720 33.0 19 16.7 10.7 11 773 29.720 17.4 10.7 11 762 35.0 21 17.1 10.6 20 788 30.0 22 17.4 10.7 18 80127.0 23 17.1 10.7 20 793 29.0 24 17.2 10.8 12 812 32.0 25 17.0 10.6  9758 34.0 26 17.1 10.7 10 780 33.4 27 17.2 10.7 13 777 31.1 28 16.8 10.7 9 782 33.6 29 16.9 10.6 11 785 33.0

As can be seen from Table 2, each of the pilot-scale samples achievedthe claimed parameters even with colloidal silica solids as high asabout 18% (Sample 16).

Example 3

A control sample and Samples 17-19 of Example 2 were utilized incomparison experiments related to first pass ash retention of each. Eachof the samples were dosed onto a cellulosic furnish.

As can be seen, a 90% first pass ash retention can be achieved usingapproximately 0.5 to 0.8 as much microparticle dosage (FPAR replacementratio) for each of Samples 17-19, as compared to the control sample.These results are graphically demonstrated in FIG. 1.

Microparticle First Pass Ash Retention (%) Dosage, lb Sample SampleSample microparicles/ton Control 17 18 19 0 73.5 73.5 73.5 73.5 0.2579.2 76.3 76.7 79.1 0.5 80.5 82.7 83.0 84.0 1 85.5 90.4 88.2 90.4 1.589.3 95.1 94.9 94.6 2 92.2 94.8 94.9 96.9

As can be seen, the inventive aqueous colloidal silica products preparedusing the inventive production method provided superior results comparedto the control sample.

To the extent that the terms “include,” “includes,” or “including” areused in the specification or the claims, they are intended to beinclusive in a manner similar to the term “comprising” as that term isinterpreted when employed as a transitional word in a claim.Furthermore, to the extent that the term “or” is employed (e.g., A orB), it is intended to mean “A or B or both A and B.” When the applicantsintend to indicate “only A or B but not both,” then the term “only A orB but not both” will be employed. Thus, use of the term “or” herein isthe inclusive, and not the exclusive use. Also, to the extent that theterms “in” or “into” are used in the specification or the claims, it isintended to additionally mean “on” or “onto.”

The general inventive concepts have been illustrated, at least in part,by describing various exemplary embodiments thereof. While theseexemplary embodiments have been described in considerable detail, it isnot the Applicant's intent to restrict or in any way limit the scope ofthe appended claims to such detail. Furthermore, the various inventiveconcepts may be utilized in combination with one another (e.g., one ormore of the first, second, third, fourth, etc., exemplary embodimentsmay be utilized in combination with each other). Additionally, anyparticular element recited as relating to a particularly disclosedembodiment should be interpreted as available for use with all disclosedembodiments, unless incorporation of the particular element would becontradictory to the express terms of the embodiment. Additionaladvantages and modifications will be readily apparent to those skilledin the art. Therefore, the disclosure, in its broader aspects, is notlimited to the specific details presented therein, the representativeapparatus, or the illustrative examples shown and described.Accordingly, departures may be made from such details without departingfrom the spirit or scope of the general inventive concepts.

All patents, patent applications, scientific papers, and any otherreferenced materials mentioned herein are incorporated by reference intheir entirety. Furthermore, the invention encompasses any possiblecombination of some or all of the various embodiments mentioned herein,described herein and/or incorporated herein. In addition the inventionencompasses any possible combination that also specifically excludes anyone or some of the various embodiments mentioned herein, describedherein and/or incorporated herein.

1. An aqueous colloidal silica product comprising water and from 16 to18 weight percent colloidal silica solids, wherein the aqueous colloidalsilica product has a viscosity ranging from about 4 to about 20 cps andan S-value ranging from 26 to 40%, wherein the colloidal silica solidshave a specific surface area ranging from 700 to 850 m²/g.
 2. Theaqueous colloidal silica product of claim 1, further comprising analkali metal.
 3. The aqueous colloidal silica product of claim 1,wherein the alkali metal is present in an amount sufficient to provide amolar ratio of silica to alkali metal ranging from 50:1 to 5:1
 4. Theaqueous colloidal silica product of claim 1, wherein the aqueouscolloidal silica product has a viscosity ranging from about 4 to about18 cps.
 5. The aqueous colloidal silica product of claim 1, wherein theaqueous colloidal silica product comprises from 17 to 18 weight percentcolloidal silica solids.
 6. The aqueous colloidal silica product ofclaim 1, wherein the aqueous colloidal silica product has a ratio ofweight percent colloidal silica solids to cps viscosity ranging from 1:2to 4:1.
 7. The aqueous colloidal silica product of claim 1, wherein theaqueous colloidal silica product has a pH ranging from 9 to
 11. 8. Theaqueous colloidal silica product of claim 1, wherein the aqueouscolloidal silica product has a pH ranging from 10 to
 11. 9. A method ofproducing an aqueous colloidal silica product, the method comprising:first, adding a first quantity of alkali metal silicate to water and apartially regenerated cationic ion exchange resin under agitation,thereby forming a first intermediate composition comprising a firstportion of aqueous colloidal silica product, wherein the firstintermediate composition has a temperature ranging from 70 to 200degrees Fahrenheit and a pH ranging from 8 to 14, and the first quantityof alkali metal silicate is added at a first rate sufficient to allowthe first addition to last for 1 to 45 minutes; second, after 0 to 90minutes, adding a second quantity of alkali metal silicate to the firstintermediate composition under agitation, thereby forming a secondintermediate composition comprising a second portion of aqueouscolloidal silica product, wherein the second intermediate compositionhas a temperature ranging from 70 to 200 degrees Fahrenheit and a pHranging from 9 to 11, and the second quantity of alkali metal silicateis added at a second rate sufficient to allow the second addition tolast for 5 to 120 minutes; after 0 minutes to 24 hours, separating thefirst and second portions of aqueous colloidal silica products from thesecond intermediate composition, thereby producing the aqueous colloidalsilica product; wherein the first quantity and the second quantitycomprise a total quantity, the first quantity ranging from 60 to 95weight percent of the total quantity.
 10. The method of claim 9, whereinthe first and second portions of aqueous silica products are separatedfrom the second intermediate composition via filtration using a screenor slotted pipe.
 11. The method of claim 9, wherein the secondintermediate composition is allowed to agitate at from 70 to 200 degreesFahrenheit for a time ranging from 0 minutes to 75 minutes.
 12. Themethod of claim 9, wherein the first intermediate composition has a pHranging from 9 to
 11. 13. The method of claim 9, wherein the first andsecond intermediate compositions have temperatures ranging from 100 to160 degrees Fahrenheit.
 14. The method of claim 9, wherein the firstrate is sufficient to allow the addition of the first quantity of alkalimetal silicate to last from 2 to 10 minutes.
 15. The method of claim 9,wherein the second rate is sufficient to allow the addition of thesecond quantity of alkali metal silicate to last from 10 to 40 minutes.16. A method of making a cellulosic sheet, the method comprising:preparing a cellulosic furnish containing from 0.01 to 1.5 weightpercent cellulosic fiber; adding to the cellulosic furnish an amount ofthe aqueous colloidal silica product of claim 1 sufficient to achieve aconcentration of colloidal silica solids of from 0.00005 to 1.5 weightpercent per dry weight of fiber in the cellulosic furnish, and an amountof a water soluble polymeric flocculant sufficient to achieve aconcentration of water soluble polymeric flocculant of from 0.001 to 5weight percent per dry weight of fiber in the cellulosic furnish,wherein the water soluble polymeric flocculant has a molecular weightranging from 500,000 to 30 million daltons; and dewatering thecellulosic furnish to obtain a cellulosic sheet.
 17. The method of claim16, wherein the amount of the aqueous colloidal silica product added tothe cellulosic furnish is sufficient to achieve a colloidal silicasolids concentration of from about 0.005 to about 1 weight percent perdry weight of fiber in the cellulosic furnish.
 18. The method of claim16, wherein the colloidal silica product has a first pass ash retentionreplacement ratio ranging from about 0.5 to about 0.8 relative to abatch aqueous colloidal silica product.
 19. The method of claim 16,wherein the colloidal silica product achieves a first pass ash retentionof at least 90% relative to a batch aqueous colloidal silica productwhen dosing microparticles into the cellulosic furnish at aconcentration of about 0.9 to 1.2 pounds per ton dry weight of fiber inthe cellulosic furnish.
 20. The method of claim 16, wherein a cationicstarch is added to the cellulosic furnish in an amount sufficient toachieve a concentration of cationic starch of from 0.005 to 5 weightpercent cationic starch per dry weight of fiber in the cellulosicfurnish.